U.S. patent number 4,207,560 [Application Number 05/936,160] was granted by the patent office on 1980-06-10 for r f area intruder detection and tracking system.
This patent grant is currently assigned to The United States of America as represented by the Secretary of the Air. Invention is credited to J. Leon Poirier.
United States Patent |
4,207,560 |
Poirier |
June 10, 1980 |
R F Area intruder detection and tracking system
Abstract
The detection, location and tracking of an intruder in an area
to be protected is accomplished by dividing the area into a
multiplicity of discrete regions, transmitting r.f. signals from
transmitting transducers that comprise lengths of transmission
lines deployed along the boundaries of the discrete regions, and
receiving intrusion occurrence signals from receiving transducers
located within each region. Violation of a boundary by an intruder
results in an intrusion signal from the receiving transducers of as
many as four possible adjacent regions thereby indicating an
intrusion event. A coincidence logic circuit indicates which
boundary has been violated. Intrusion occurrence signals are stored
for suitable periods of time while past and current intrusion
events are indicated on a display in order to locate and track
intruders.
Inventors: |
Poirier; J. Leon (Chelmsford,
MA) |
Assignee: |
The United States of America as
represented by the Secretary of the Air (Washington,
DC)
|
Family
ID: |
25468252 |
Appl.
No.: |
05/936,160 |
Filed: |
August 23, 1978 |
Current U.S.
Class: |
340/552; 333/237;
340/525; 343/771 |
Current CPC
Class: |
G08B
13/2497 (20130101) |
Current International
Class: |
G08B
13/24 (20060101); G08B 013/24 () |
Field of
Search: |
;340/552,525,524,541,24
;343/771 ;333/237 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Swann, III; Glen R.
Attorney, Agent or Firm: Rusz; Joseph E. Goldman; Sherman
H.
Government Interests
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or
for the Government for governmental purposes without the payment of
any royalty thereon.
Claims
I claim:
1. An intrusion detection system for detecting and locating
intrusion events in an area to be protected comprising a
multiplicity of electromagnetic wave transmitting transducers
deployed to cover the area to be protected with a pattern of
discrete enclosed regions, said transmitting transducers being
lengths of transmission line defining region boundaries,
an electromagnetic wave transmitter feeding said transmitting
transducers,
an electromagnetic wave receiving transducer within each discrete
region,
a receiver connected to each receiving transducer, each said
receiver generating an output signal in response to the violation
by an intruding agent of any boundary defined by a transmitting
transducer adjacent that receiver's receiving transducer, and
a coincidence logic circuit receiving the outputs of said receivers
and being adapted to develop an intrusion occurrence signal for
each region boundary in response to the coincident outputs from
adjacent receiving transducers.
2. An intrusion detection system as defined in claim 1 including a
display of the area to be protected having intrusion occurrence
indicators, said indicators being actuated in response to said
intrusion occurance signals.
3. An intrusion detection system as defined in claim 2 including
intrusion occurrence signal storage means for retaining intrusion
occurrence and location information, said storage means receiving
outputs from said coincidence logic circuit and feeding said
intrusion occurrence indicators.
Description
BACKGROUND OF THE INVENTION
The system of the present invention provides for the first time the
ability to track an intruder after he has crossed a perimeter
boundary. It uses a grid of leaky coaxial cables as sensors and
provides location information by identifying the specific
subboundary within the grid which was crossed with a coincidence
location logic circuit. The system further provides a method of
detecting and locating an intrusion not only across a perimeter
boundary, but also within the boundary. No system now exists to
track an intruder within the zone perimeter. It is noted this
system can be used to provide a high level of security for a number
of applications and installations such as aircraft parking ramps,
material storage areas, and missile launch complexes, etc.
SUMMARY OF THE INVENTION
A system for R F area intruder detection and tracking is provided.
The area to be protected is divided into a number of smaller cells.
Certain cells may be omitted to allow for building or other terrain
features. Each cell consists of a transmitting transducer and a
receiving transducer. The presence of an intruder near the boundary
of a cell causes the signal coupled from the transmitting to the
receiving transducer to change. This changing signal is processed
in the receiver to produce an "intruder present" output. All
receiver outputs may be monitored in a coincidence location logic
array which identifies the precise boundary which was crossed.
These outputs may be supplied to a display board through a latch
circuit which remembers the location of past intrusions, thus
providing a visual track of the intruder.
DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a layout for a preferred system;
FIGS. 2A and 2B each show a separate cell loop configuration,
FIG. 3 shows the receiver transmitter block diagram;
FIG. 4 shows the coincidence logic circuit;
FIG. 5 shows a block diagram of the latch and display driver;
and
FIG. 6 shows a display board.
DESCRIPTION OF THE PREFERRED EMBODIMENT
To clarify the preferred system, the rows and columns of the cell
array are designated by numbers and letters as shown in FIG. 1. For
example, receiving sensor BC' is in the second row, third column.
The boundary between sensor BC' and BD' is designated B3' etc.
Thus, an intrusion across the subboundary .phi.C' can only produce
an output from sensor AC'. Similarly, an intrusion across B2' will
produce an output from both BB' and BC'. Therefore, it is only
necessary to test the signal changes from each of the receiving
sensors for coincidence to identify the boundary which was crossed.
It is noted there are shown receiving antennas 10-31 and
transmitting sensor feedpoints 32-42.
Two transmitting-receiving transducers are shown in FIGS. 2A and
2B. In FIG. 2A, the transmitting transducer is a leaky coaxial
cable loop which is terminated in matched load 51. The receiving
transducer is centrally located antenna 52. There is also
transmitter 53 connected to transmitting transducer feedpoint 54.
Receiver 55 is connected to receiving antenna 52. The output from
the receiver may be utilized in coincidence location logic. In FIG.
2B, the receiving transducer is replaced by leaky coaxial cable 60
parallel to and separated from the transmitting sensor which is
leaky coaxial cable 61. Each of these configurations has certain
advantages and other types and configurations are possible. It is
further noted that receiver 62 is connected to leaky coaxial cable
60 which is terminated in matched load 64 and transmitter 63 is
connected to feed point 65 and then to leaky coaxial cable 61 which
is terminated by matched load 66.
Subsequent transmitting transducers can be fed from previous
transducers by inserting line amplifiers and power dividers in
place of the termination. Any number of interconnection plans can
be formulated. The roles of the transmitting and receiving
transducers can be interchanged, although using a leaky coaxial
cable as the transmitting transducer in the system of FIG. 2A has
the advantage of keeping the effective radiated energy low.
The transmitter may be typically a low power CW solid state unit
operating in the VHF range. The receiver may be any one of several
types (crystal video, TRF, super heterodyne etc.) depending upon
the size of the cells. Coherent detection and long time constant a
g c may be of advantage to enhance rejection of interfering signals
and reduce the effect of slow changes in ambient environmental
conditions. A representative arrangement is shown in FIG. 3 in
which transmitter 70 feeds all the transducers of FIG. 1, there is
shown receivers 10 through 31 for FIG. 1 each one receiving a
signal from antennas 10 through 31, respectively. Channel 10
through 10d is described, and it is also applicable to channel 31
through 31d. The signal from receiver 10 is fed to detector 10a
which also receives a signal from transmitter 70. Detector 10a
provides a g c for receiver 10. Bandpass filter 10b passes the
output signal from detector 10a to threshold detector 10c for
application to alarm shaper 10d and then it is received by logic
and display. The detector output is filtered to allow any changes
which could be produced by human motion to be passed into the
threshold detector. The alarm shaper is a retriggerable one-shot
which is timed to assure the existence of an alarm signal for a
sufficiently long time to complete coincidence testing.
An implementation of the coincidence location logic array for the
cells in the upper left hand corner of FIG. 1 is shown in FIG. 4.
An intruder can produce an alarm signal in up to four cells
simultaneously, so it is necessary to test the outputs from each
cell for coincidence with the output of another adjacent cell.
Coincidence identifies the intruder location as that boundary
common to the cells which display an output in their alarm outputs.
AND gates 80-85 are illustrative and indicate the operation for
some of the representative cells of FIG. 1.
The outputs from the coincidence location logic, each corresponding
to a cell subboundary, operate a latch which controls the display
lamp driver. This arrangement is shown in FIG. 5. The latch is
required to store the intrusion location after the intruder leaves
that location. Each latch can be manually reset by an operator when
required. The coincidence location logic of FIG. 4 is shown as
component 89. It feeds latches 90 through 90x. Latch reset 92 is
shown as available to latches 90 through 90x. Each of the latches
possess an output to the respective drive. Drivers 91 through 91x
are utilized for latches 90 through 90x, respectively. The outputs
from drivers 91 through 91X may be fed to display 92.
One type of display board is shown in FIG. 6 in which a set of LED
indicators indicated by circles is superimposed on an outline map
of the area to be protected which shows fence 100, warehouse 101,
parking 102, road 103 and trees 104. Each output from the
coincidence logic network controls one of the LED indicators and
the latch keeps the indicator on once it is alarmed. As the
intruder moves about another LED comes on to record his new
location. An operator-initiated reset control extinguishes the LED
indicators at the end of a track.
* * * * *